Self-destruct fuze delay mechanism

ABSTRACT

An exemplary self-destruct fuze delay for a submuntion includes an ampoule filled with an activation fluid, a spring-loaded pin to break the ampoule upon deployment of the munition, and a wick to collect and retain the activation liquid in contact with a spring loaded restraining link having an embedded firing pin. The activation liquid contacts the restraining link, preferably via the wick. The action of the activation liquid on the restraining link over time causes the link to fail at the predetermined location, allowing a severed portion with the embedded firing pin to move under force (e.g., spring, gas) and impact or initiate a secondary detonator. The secondary detonator is in close proximity to a primary detonator typically used to initiate a main charge of the submunition. Initiation of the secondary detonator destroys the primary detonator and, depending upon slide location, either sterilizes the submunition, or destroys the entire submunition.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to fuzes for submunissions of the typewhich are disbursable by a vehicle such as a projectile or carriershell, and in particular, to a self-destructing fuze that automaticallyself-destructs or self-neutralizes the submunition if the primary modeof detonation fails.

2. Description of Related Art

For many years, submunitions included in the family of ImprovedConventional Munitions (ICM) employed a simple, low cost pointdetonating fuze for initiating a main charge upon impact. Reliability ofthe fuze was in the 95% range, meaning fairly large quantities ofsubminitions would not function for various reasons. This failure rateof about 5% presents both an environmental and a humanitarian hazard.Hazardous duds (e.g., armed but unexploded submunitions) remained on thebattle field indefinitely and with potentially undesirable consequencesto friendly troops and/or civilians.

The currently used M223 fuze incorporated unique and effective safetyfeatures for personnel and property protection during the manufacturingand loading process. Key among these safety features is a stabilizerribbon attached to an arming screw that, in its engaged position, locksa detonator-containing slide in an unaligned position, therebypreventing any possible contact of a primary firing pin with thedetonator. Upon deployment of the submunition from its carrier (e.g.,howitzer projectile) the stabilizer ribbon becomes exposed to the airstream wind resistance and unfurls. The combination of wind resistance,induced spin of the submunition, and/or vibration causes the submunitionto rotate relative to the ribbon, causing an arming screw to back out,which in turn releases a spring loaded slide that shifts, allowing thefiring pin to align with the detonator. Upon impact, the firing pin,which is typically attached to a small weight, drives into the detonatorcausing initiation of the main charge.

In the case of projectile carrier, the entire submunition is spinning ata very high rate at ejection and the ribbon's resistance to spinningcauses the arming screw to back out. However, a missile is a non-spincarrier so rotation is not available to arm the unit. Instead, thearming screw backs out because of the vibration induced as thesubmunition descends. That is, a loose fit between the arming screw andweight allows the arming screw to back out, which releases the springloaded slide to align the firing pin with the detonator.

The failure of the armed submunitions described above results inhazardous duds. Incidence of death and injury to innocent victims fromsuch hazardous duds, coupled with an international moratorium onantipersonnel mines, demonstrates a need to find a solution that wouldminimize these residuals on the battle field. It would be beneficial toprovide a Self-Destruct Fuze (SDF) that, in the event of failure of thefuze in the primary mode, would cause a secondary action to eitherexplode the entire submunition or at least destroy the detonator (e.g.,sterilize the submunition, otherwise referred to as sterilization).

U.S. Pat. No. 5,373,790, to Chemiere, et al., discloses a mechanicalsystem for self-destruction of a submunition, having a warhead initiatedby a pyrotechnic sequence, a main striker and a priming device composedof a slide movable between a safety position and an armed position, andwhich has a device for priming the charge. The self-destruction systemincludes a secondary striker mounted inside a receptacle of the slide,and a control device that releases the secondary striker after a delay.The secondary striker is integral with a holding element held abutting aseat by the urging of an arming spring. The control device of thesecondary striker has a corrosive agent stored in a glass ampoule that,when broken by the holding element, chemically attacks the holdingelement to release it from its seat. When the holding element isreleased, the arming spring moves the secondary striker to contact thedetonator and destroy the munition.

U.S. Pat. No. 4,653,401, to Gatti, discloses a self-destructing fuzehaving a first striker member movable within the body of the fuze andable to come into contact with a detonator to cause it to explode, and aslide that is movable in a direction substantially orthogonal to thedirection in which the first striker member is movable. A second strikermember is disposed in the slide, and is movable from a first position inwhich it elastically deforms a spring and is held at a predetermineddistance from the detonator, to a second position in which it comes intocontact with the detonator to cause it to explode. The movement of thesecond striker member is delayed by a section of wire that under a forceexerted by the spring is plastically deformed over time. The plasticdeformation eventually frees the second striker member allowing itsmovement to the second position and against the detonator to cause it toexplode.

U.S. Pat. No. 5,932,834, to Lyon, et al., discloses an auto-destructfuze that provides a primary mode detonator and a delayedauto-destruct/self-neutralize mode detonator for a grenade. Themechanics for the primary mode detonator is similar to the M223 fuze.Operation of the auto-destruct/self-neutralize is based on a LiquidAnnular Orifice Device (LAOD) that is released from a locked positionupon expulsion of the LAOD from a storage container. The LAOD movesslowly under the urging of a spring and eventually releases a clean-upfiring pin which activates a clean-up detonator to activate the primarymode detonator and destructs or self-neutralizes the grenade.

U.S. Pat. No. 4,998,476, to Rudenauer, et al., discloses a fuze for abomblet including a slide having a detonator triggered in response to animpact and which undergoes a transition during the free flight of thebomblet from a safe position into an armed position. The slide alsoincludes a hydraulic or pneumatic cylinder-piston retarding device and aspring biased self-destruct pin which is operatively coupled to thedevice and has a self-destruct detonator associated therewith. Theretarding device is freed upon movement of the slide to the armedposition, and releases the movement of the self-destruct pin after atime delay to trigger the self-destruct detonator and, if needed, theprimary detonator.

Numerous variations of self-destruct (SD) devices, working inconjunction with proven safety features of the stabilizer ribbon armingscrew, and sliding arrangement have been developed with various degreesof success. In one variant, the SD feature centers around amicroelectronic battery and circuit with a complicated attendantinitiating device. Two other variants employ a critical pyrotechnicdelay column to achieve the necessary time lapse. Even if successful,the critical manufacturing process and high costs of these candidatesraise long term and expensive productabilty concerns.

Even with the current self-destruct fuze development, it would still bebeneficial to provide reliable low-cost and improved self-destruct delaydevices or mechanisms for automatically destroying or self-neutralizingsubmunitions after a time delay to minimize undesirable consequences tofriendly troops and/or civilians. All references cited herein areincorporated herein by reference in their entireties.

BRIEF SUMMARY OF THE INVENTION

In accordance with the preferred embodiments of the invention, aself-destruct fuze delay device for a submunition is provided, with thesubmunition having a longitudinal access, a main charge, and adetonating fuze with a movable slide for initiating the main charge uponimpact. The self-destruct fuze delay device includes a detonator mountedto the fuze slide, a delay mechanism arranged within the submunitionoffset and substantially orthogonal to the submunition's longitudinalaxis, and an activation mechanism. The delay mechanism includes anenergizing source (e.g., compression spring, gas chamber), a restraininglink (e.g., plunger, rod), and a self-destruct firing pin attached tothe restraining link at a first portion thereof proximate to thedetonator. The restraining link also has a second portion longitudinallyextending from the first portion away from the detonator and attached tothe fuze slide. The first portion is movable from a first position, inwhich it is held by it attachment to the second portion at apredetermined distance from the detonator, to a second position in whichthe first portion is separated from the second portion and theself-destruct firing pin is urged toward the detonator by the energizingsource. The activation mechanism separates the first portion from thesecond portion after a predetermined delay, with the second portionremaining attached to the fuze slide after separation from the firstportion.

While not being limited to a particular theory, the activation mechanismmay include a container (e.g., glass ampoule) holding a fluid (e.g.,acid, solution, reactant, liquid) for corroding the restraining linkbetween the first portion and the second portion to separate the firstportion form the second portion, and a breaking member (e.g., ampouleweight that impacts the container to release the fluid toward therestraining link). Moreover, this embodiment may also include a wickadjacent the restraining link at a predetermined area between the firstportion and the second portion that collects the fluid from thecontainer and isolates the collected fluid onto the predetermined areato facilitate the corroding of the restraining link. In accordance withthe preferred embodiments, the detonating fuze may also have a maindetonator in the fuze slide moveable between a safety position and anarmed position, wherein the urging of the self-destruct firing pintoward the detonator by the energizing source causes the detonator toexplode, which causes the main detonator to explode.

In another preferred embodiment of the invention, a self-destruct fuzedelay device is provided, preferably for a submunition having alongitudinal axis, a main charge and a detonating fuze having a movableslide for initiating a main charge upon impact. The self-destruct fuzedelay includes a detonator mounted to the fuze slide, a delay mechanismarranged within the submunition substantially orthogonal to thesubmunition's longitudinal axis, and an activating mechanism. The delaymechanism includes an energizing source (e.g., compression spring,pressurized gas container), a restraining link (e.g, piston, rod) havinga first end attached to the self-destruct firing pin and a second endattached to the fuze slide. The restraining link is moveable from afirst position, in which it is held by its attachment to the fuze slideat a predetermined distance from the detonator, to a second position inwhich the restraining link is separated from its attachment to the fuzeslide and the self-destruct firing pin is urged toward the detonator bythe energizing source. The activation mechanism separates therestraining link from its attachment to the detonating fuze slide. Theactivation mechanism includes a container (e.g., glass ampoule) holdinga fluid (e.g., acid, solution, liquid) for corroding the restraininglink, and a wick adjacent a predetermined area of the restraining link,with the wick being porous to absorb and draw the fluid from thecontainer onto the restraining link at the predetermined area tofacilitate the corroding and separation of the restraining link fromattachment to the fuze slide.

While not being limited to a particular theory, the restraining link ofthis preferred embodiment may include a first portion proximate to thedetonator, a second portion distal to the detonator and attached to thefuze slide, with the first portion and the second portion defined by thepredetermined area. In this arrangement, the restraining link isseparated from its attachment to the fuze slide at the predeterminedarea with the second portion remaining attached to the fuze slide afterthe separation. In the preferred embodiments, the predetermined areabetween the first portion and the second portion is preferablystructurally weaker (e.g., undercut, thinner) than the first portion andthe second portion to pulling forces along the longitudinal axis of therestraining link.

Another preferred embodiment of the invention includes a method or meansfor self-destructing a detonator of the submunition having a detonatingfuze with a moveable slide upon deployment into the air. The methodincludes releasing an activation liquid from a container, absorbing theactivation liquid with a porous wick, directing the absorbed activationliquid onto a predetermined area of a restraining link having a firingpin and held in place via attachment to the fuze slide, corroding thepredetermined area with the directed activation liquid, separating therestraining link at the predetermined area, urging the firing pin towardthe detonator, and colliding the firing pin into the detonator todestroy the detonator. The method may also include separating therestraining link at the predetermined area into a first portion havingthe firing pin and the second portion remaining attached to the fuzeslide.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

The invention will be described in conjunction with the followingdrawings in which like reference numerals designate like elements andwherein:

FIG. 1 is a top sectional view of the self-destruct fuze delay device inaccordance with the preferred embodiments;

FIG. 2 is a side sectional view of the self-destruct fuze delay deviceshown in FIG. 1;

FIG. 3 is another side sectional view orthogonal to the view of FIG. 2of the self-destruct fuze delay device;

FIG. 4 is an exploded view of a delay mechanism for the preferredself-destruct fuze delay device;

FIG. 5 is an exploded view of an activation liquid assembly for thepreferred self-destruct fuze delay device;

FIG. 6A is a side sectional view of the delay mechanism at a firststate;

FIG. 6B is another side sectional view of the delay mechanism at asecond state;

FIG. 6C is yet another side sectional view of the delay mechanism at athird state;

FIG. 6D is still another side sectional view of the delay mechanism at afourth state;

FIG. 7 is a top sectional view of another preferred embodiment of theself-destruct fuze delay device;

FIG. 8 is a side view partially in section of an exemplary fuze delaydevice before deployment into the atmosphere;

FIG. 9 depicts the fuze device shown in FIG. 8 from a side viewsubstantially orthogonal to the view of FIG. 8;

FIG. 10 is a flow diagram depicting an exemplary function sequence ofevents for the self-destruct fuze delay device of the preferredembodiments;

FIG. 11 is a side view of the exemplary fuze delay device shown in FIG.8 after deployment;

FIG. 12 is a side view of the exemplary fuze delay device shown in FIG.9 after deployment;

FIG. 13 is a side view of the exemplary fuze delay device of FIG. 7after breaking of the reactant container; and

FIG. 14 is a side view of the exemplary fuze delay device of FIG. 13after separation of the restraining link.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Exemplary embodiments for a self-destruct fuze delay device aredescribed with reference to FIGS. 1-13. While not being limited to aparticular theory, in general, an exemplary self-destruct fuze delay fora submuntion includes an ampoule filled with an activation fluid (e.g.,reactant, acid, solution, liquid), a spring-loaded pin to break theampoule upon deployment of the munition, and a wick to collect andretain the activation fluid in contact with a spring loaded restraininglink having an embedded firing pin. The activation fluid contacts therestraining link, preferably via the wick, at a predetermined area thatis preferably weakened (e.g., undercut). The action of the activationfluid on the restraining link causes the link to fail at thepredetermined area, allowing a severed portion with the embedded firingpin to move under force (e.g., spring, gas) and impact or initiate adetonator (e.g., M55). The detonator is in close proximity to a primarydetonator (e.g., M55) typically used to initiate a main charge of thesubmunition. Initiation of the detonator, which is a secondarydetonator, destroys the primary detonator and either sterilizes thesubmunition, or depending upon slide location, destroys the entiresubmunition.

The time required for the activation fluid to react with the restraininglink and achieve failure at the predetermined location of therestraining link is the predetermined time necessary to satisfy desireddelay requirements for the self-destruct fuze. The primary fuze alsoretains the positive operation of the M223 fuze, that is, it utilizesthe stabilizer ribbon, firing pin and slide to retain the knownout-of-line safety features.

Although the preferred self-destruct fuze delay device is applicable toall the various ICM items, in the interest of brevity, the exemplaryself-destruct fuze devices are generally tailored toward use in theGuided Multiple Launch Rocket System (GMLRS). The GMLRS warheadtypically contains 404 submunitions, each with its own self-destruct(SD) fuze. While not being limited to a particular theory, thesubmunitions typically are disbursed via a center core burster thatexplodes in flight creating ample pressure to burst the warhead casing,and allowing the currently-used submunition's random dispersion into theatmosphere.

In general, as each submunition is disbursed into the atmosphere, theimpact of the air stream causes the submunition's stabilizer ribbon tounfurl, allowing an arming screw to back out and a slide to move to itsarmed position. Upon impact, the firing pin is free to pierce theprimary detonator and cause a subsequent main charge explosion, whichdestroys the submunition. Damaged fuzes and fuzes that arm properly butcome into contact with the ground or a target via side impact may failto initiate the main charge resulting in residual hazardous duds. Ahazardous dud is a submunition that still has its fuze attached and itsprimary detonator present that together could potentially initiate themain charge. A hazardous dud is different than an unexploded ordinance,which is a submunition that has no means of initiation (e.g., primarydetonator is missing or destroyed).

The delay necessary for the activation liquid to corrode the restraininglink to failure (e.g., about 25 seconds minimum to 30 minutes) isgreater than the foreseeable flight time of the submunition, which endswhen the submunition reaches the ground or target. This delay allows theprimary detonator to initiate the main submunition charge when thesubmunition strikes the ground or target. The self-destruct fuze delaydevice is designed to destroy the submunition if the submunition failsto explode after it strikes the ground or target.

Other advantages, characteristics and details of the invention willemerge from the explanatory description thereof provided below withreference to the attached drawings and examples, but it should beunderstood that the present invention is not deemed to be limitedthereto. Toward that end, FIG. 1 depicts an exemplary self-destruct fuzedelay device 10 as a detonating fuze 14 encased within a submunition 12.The submunition 12 includes a fuze slide 16 housing a primary detonator18 that is movable with the slide between a safety position (shown),where the primary detonator is not aligned with a main striker 20, andan armed position, where the primary detonator is located opposite themain striker and aligned along the longitudinal axis of the submunitionbetween the main striker and the submunition. The slide 16 also housesthe self-destruct (SD) fuze delay device 10.

Still referring to FIG. 1, the SD fuze delay device 10 includes asecondary detonator 22 aligned with a delay mechanism 24 that isarranged in the slide 16 offset and substantially orthogonal to thelongitudinal axis of the submunition 12. The SD fuze delay device 10also includes an activation mechanism 25 adjacent the delay mechanism 24for activating the delay mechanism and causing the secondary detonator22 to explode. The explosion of the secondary detonator 22 activates theprimary detonator 18, causing it to explode and set off the main charge20 if the primary detonator is aligned therewith. Preferably, thesecondary detonator 22 remains adjacent the primary detonator 18regardless of the position of the primary detonator to ensure thatoutput from an explosion of the second detonator initiates the primarydetonator. This ensures one of the three potential outcomes upondispersion of the submunition 12 into the atmosphere, as set forthbelow.

If the detonating fuze 14, which includes the primary detonator 18, theslide 16, and the primary striker 20, functions normally, thesubmunition 12 explodes and the SD fuze delay device 10 is destroyed inthe process. If the detonating fuze 14 functions normally to the pointthat the slide 16 moves into its armed position, but the submunition 12fails to explode, the SD fuze delay device 10 will initiate the primarydetonator 18 and, in turn, will then fire the main charge to explode thesubmunition. If the detonating fuze 14 does not function normally sothat the slide 16 remains in the safety position or does not reach thearmed position, then the SD fuze delay device 10 will initiate theprimary detonator 18 but likely not the main charge, resulting in asterilized submunition or unexploded ordinance.

Referring in particular to FIGS. 1 and 2, the delay mechanism 24includes a restraining link 26, a secondary firing pin 28 and acompression spring 30. The secondary or self-destruct firing pin 28 isattached to a front end 29 of the restraining link 26, which istransitionally movable in a receptacle or channel 32 of the slide 16. Ascan best be see in FIGS. 1, 2 and 6, the secondary firing pin 28 ispartially embedded in a piston 34 of the restraining link 26. The piston34 is extended opposite the secondary firing pin 28 by an axial rod 36which freely passes inside the compression spring 30 and is attached atits distal end 38 to the slide 16 via a retainer pin 40. Preferably, theretainer pin 40 slides through a transverse opening of the axial rod 36and within a spring retainer 40 that holds the compression spring 30,retainer pin 40 and axial rod 36 together and seated against an innerwall 44 of the slide 16. The compression spring 30 is mounted in atensioned state around the axial rod 36 and is positioned between thepiston 34 and spring retainer 42 to urge the piston, and thus therestraining link 26 and the secondary firing pin 28 toward the secondarydetonator 22. Before deployment, a lockout pin 46 is attached to theslide 16 and abuts the first end 29 of the restraining link 26 toprevent movement of the restraining link towards the secondary detonator22.

While not being limited to a particular theory, the axial rod 36includes a weakened area 48 that defines a first portion 50 and a secondportion 52 of the restraining link 26. The first portion 50 is proximateor adjacent to the secondary detonator 22 and includes the secondaryfiring pin 28, the piston 34 and part of the axial rod 36 extending fromthe piston. The second portion 52 is distal or away from the secondaryfiring pin 28 and is fixedly attached to the slide 16 via the retainerpin 40. The weakened area 48 is a predetermined part of the axial rod 36that is constructed weaker than the remainder of the axial rod to failupon application of a reactant (e.g., corrosive agent, acid, solution)and release the first portion 50 toward the secondary detonator 22. Forexample, the weakened area may include a circumferential plane or ringsection that is undercut (e.g., having walls thinner than the walls ofthe adjacent first and second portions). Furthermore, a wick 54 ispositioned adjacent, and preferably encircles the weakened area 48. Thewick 54 is made of a porous material that absorbs the reactant fluid anddirects it to the weakened area 48 to facilitate the corrosion of therestraining link 26 at the weakened area, as is described, for example,in greater detail below.

As can best be seen in FIGS. 1 and 3, the SD fuze delay device 10 alsoincludes an activation mechanism 25 that communicates with and, after adelay, releases the first portion 50 of the restraining link 26 from thesecond portion 52, which allows the compression spring 30 to urge thesecondary firing pin into the secondary detonator 22. While not beinglimited to a particular theory, the activation mechanism is offset fromthe channel 32 that houses the delay mechanism 24. The activationmechanism 25 includes a container 56 (e.g., glass ampoule) holding areactant fluid 58. The reactant fluid 58 is a corrosive agent (e.g.,acid or solution of liquid or gas) that when placed in contact with theretraining link, causes the axial rod 36 to corrode, fail and break,preferably at the weakened area 48, thereby allowing the compressionspring 30 to separate and move the piston 34 and the secondary firingpin 28 toward the secondary detonator 22 and activate the detonator uponimpact.

The activation mechanism 25 also includes an ampoule weight 60, acompression spring 62 and a spring retainer clip or pin 64. In theexemplary embodiment of FIGS. 1 and 3, and the exploded view of FIG. 5,the compression spring 62 is mounted in a tension state around theampoule weight 60 between a shoulder 66 of the ampoule weight and aninner wall 68 of the slide 16. The spring retaining pin 64 keeps thecompressed spring 62 in its tensioned state, and thereby keeps thecontainer 56 safe from impact by the ampoule weight 60. The ampouleweight 60 is a breaking member that, but for the spring retainer pin 64,is urged by the compression spring 62 into impact with the container 56,causing the container to break and release the reactant fluid 58.Therefore, when placed as shown in FIGS. 1 and 3, the spring retainerpin 64 prevents activation of the SD fuze delay device 10. In additionto breaking the container 56, ampoule weight 60 also preferably acts asa plunger and pushes the released fluid 58 toward the delay mechanism 24whereupon the fluid is absorbed by the wick 54 and corrodes the weakenedarea 48 to release the first portion 50 toward the secondary detonator22.

FIG. 4 is an exploded view of the delay mechanism 24, the secondarydetonator 22 and the wick 54. FIG. 5 shows an exploded view of theactivation mechanism 25. FIGS. 4 and 5 are provided to help show thestructure and association of the elements of the SD fuze delay device10. FIGS. 6A-D illustrate a sequence of the delay mechanism 24 with thesecondary detonator 22 and the wick 54 from a time prior to deploymentof the submunition 12 to initiation of the secondary detonator, as willbe described in greater detail below.

Upon deployment of the submunition 12, the self-destruct fuze delaydevice 10 self-destructs the submunition after a preset delay if thesubmunition fails to explode upon its impact with the ground or atarget. FIG. 6A depicts the delay mechanism 24 before deployment intothe atmosphere. When an exemplary submunition 12 hits the air stream atdeployment, the spring retainer pin 64 and the safety lockout pin 46 arereleased out of their predeployment positions by the unfurling of thestabilizer ribbon or a secondary ribbon. The pins 46, 64 may otherwisebe released by alternative known approaches. As is readily understood bya skilled artisan, this releases the compression spring 62 and removesthe lockout from the delay mechanism 24.

Upon its release, the compression spring 62 drives the ampoule weight 60into the container 56, breaking the container and releasing the reactantfluid 58 to flow into and be absorbed by the felt wick 54. To helpfacilitate the flow of the released fluid 58 to the wick 54, a channelis provided therebetween, and preferably the ampoule weight 60 acts as aplunger and pushes the fluid through the channel to the wick. In otherwords, after breaking the container 56, the compression spring 62continues to drive the ampoule weight 60, forcing the fluid 58 into thewick 54. At this time, the delay mechanism 24 appears as depicted inFIG. 6B, with the safety lockout pin 46 removed and the reactant fluid58 flowing towards the wick 54.

The wick 54 encircles the weakened area 48 of the restraining link 26allowing the reactant fluid 58 (e.g., activation liquid) to communicatewith and attack (e.g., corrode) the axial rod 36 at the weakened area48. FIG. 6C depicts the delay mechanism 24 with the wick 54 saturatedwith the fluid 58 that communicates with and attacks the axial rod 36.Over a predetermined minimum time delay (e.g., between about 25 secondsand 30 minutes) the axial rod 36 weakens to the point of failure andbreaks, preferably at or about the weakened area 48. Upon the failure ofthe axial rod 36, the compression spring 30 drives the secondary firingpin 28 toward the secondary detonator 22, causing the firing pin toimpact and explode the secondary detonator. See FIG. 6D, which depictsthe delay mechanism 24 at impact with the seconday detonator 22 afterthe failure of the axial rod 36.

Output from the exploded secondary detonator 22 initiates the adjacentprimary detonator 18, causing it to explode and sterilize thesubmunition. If at this time the fuze slide 16 is in its armed position,such that the primary detonator 18 is aligned with the main charge, thenthe initiation of the primary detonator from the secondary detonator 22will then fire the submunition 12. Accordingly, the SD fuze delay device10 is reliable since it ensures either sterilization or destruction ofthe submunition 12 depending on the relationship between the primarydetonator 18 and the main charge.

FIGS. 7-13 depict a preferred embodiment of the self-destruct fuze delaymechanism. The drawings of the preferred embodiment exemplified in FIGS.7-13 and in the embodiment exemplified in FIGS. 1-6 include likereferenced numerals which designate like elements and which may not befurther described to avoid unnecessary repetition.

FIG. 7 shows an exemplary self-destruct fuze delay device 100 as adetonating fuze 102 for use with a submunition. Like the delay device 10discussed above, the delay device 100 is housed in a fuze slide 16having a primary detonator 18 that is movable with the fuze slidebetween a safety position (shown), where the primary detonator is notaligned with a main striker 20, and an armed position, where the primarydetonator is adjacent the main striker and preferably aligned along thelongitudinal axis of the submunition with the main striker. The delaydevice 100 includes a secondary detonator 22 aligned with a delaymechanism 104 that is arranged in the fuze slide 16 offset andsubstantially orthogonal to the longitudinal axis of the submunition.The delay device 100 also includes an activation mechanism 106 offsetand in fluid communication with the delay mechanism 104 for activatingthe delay mechanism and causing the secondary detonator 22 to explode.While not being limited to a particular theory, the fuze slide 16 shownin FIG. 7 houses the secondary detonator 22, the delay mechanism 104 andthe activation mechanism 106 in a generally U-shaped aperture 108 boredinto the fuze slide and defined by an inner wall 120 of the fuze slide.The fuze slide 16 includes a closure plate 122, preferably formed of aplastic or metal, that is bonded (e.g., by adhesives, crimping,friction, heat) to the inner wall 120 defining the aperture 108 to sealthe secondary detonator 22, the delay mechanism 104 and the activationmechanism 106 within the aperture.

As noted above, the explosion of the secondary detonator 22 activatesthe primary detonator 18, causing it to explode and set off the maincharge if the primary detonator is aligned therewith. Preferably, thesecondary detonator 22 remains adjacent the primary detonator 18regardless of the position of the primary detonator to ensure thatoutput from an explosion of the second detonator initiates the primarydetonator. This ensures one of the previously discussed potentialoutcomes upon dispersion of the submunition into the atmosphere.

Still referring to FIG. 7, the delay mechanism 104 includes acompression spring 30 as an energizing source, and a restraining link114 extending from the closure plate 122 to a secondary firing pin 28.The secondary or self-destruct firing pin 28 defines a front end of anaxial rod 110 proximate the secondary detonator 22. The axial rod 110 ismovable in a receptacle or channel 32 of the slide 16, and includes thesecondary firing pin 28 and a piston 112 abutting a compression spring30 as set forth in greater detail below.

The axial rod 110 extends away from the secondary detonator 22 from thesecondary firing pin 28, freely passes inside the compression spring 30and is attached at its distal end 38 to the closure plate 122 of thefuze slide 16 via the restraining link 114 as set forth in greaterdetail below. The axial rod 110 and compression spring 30 are partiallyembedded in a cylindrical sleeve 124 of the piston 112, which extendsaway from the secondary firing pin 28 to form the cylindrical sleevehaving a central bore that partially houses the axial rod andcompression spring 30 therein. The compression spring 30 is mounted in acompressed state around the axial rod 110 and is positioned between thepiston 112 and the closure plate 122 of the fuze slide 16 to urge thepiston, and thus the axial rod and the secondary firing pin 28 towardthe secondary detonator 22. As can best be seen in FIG. 7, thecylindrical sleeve 124 terminates at a flanged rim 116 extendingradially outward to define a shoulder 118. Before deployment, as shownin FIG. 7, the shoulder 118 abuts a safety lockout pin 46 that slidesthrough a transverse opening in the fuze slide 16 and prevents movementof the secondary firing pin 28 towards the secondary detonator 22.

While not being limited to a particular theory, the restraining link 114holds the axial rod 110 to the closure plate 122. The restraining link114 is preferably a styrene based (e.g., polystyrene) shaft embedded andsealed (e.g., adhesively, frictionally) to aligned counter bores 126,128 in the closure plate 122 and the axial rod 110, respectively. Assuch, the restraining link 114 is a weakened area that fails underchemical attack and breaks to release the firing pin and axial rod 110from the closure plate 122. When broken, the restraining link 114separates into two sections, which define adjacent edges of first andsecond portions 130, 132 of the restraining link. The first portion 130is attached to the axial rod 110 which is attached to the secondaryfiring pin 28. The second portion 132 is distal or away from thesecondary firing pin 28 and is attached to the closure plate 122.

The restraining link 114 is constructed of a material vulnerable to areactant (e.g., corrosive agent, acid, solution), in particular, incomparison to the other elements of the delay mechanism 104 discussedabove, to fail over time under application of the reactant. While notbeing limited to a particular theory, the reactant erodes therestraining link 114, causing the restraining link fail or break underthe pulling stress of the compression spring 30 and release the firstportion 130 toward the secondary detonator 22 (FIG. 11). Furthermore, awick 54 is positioned adjacent, and preferably encircles the restraininglink 114 between the axial rod 110 and the closure plate 122. The wick54 is made of a porous material that absorbs and directs the reactantfluid 58 to the restraining link 114 to facilitate the erosion andfailure of the restraining link, as described, for example, in greaterdetail below. It should be understood that the wick 54 is not criticalto the operation of the fuze delay device 100, as the use of the wick isnot required for the reactant fluid 58 to access and erode therestraining link to failure. However, the use of the wick 54 or anequivalent thereto is preferred to direct and focus the reactant fluid58 onto the restraining link 114 for improved control and uninterruptedcommunication there between.

Still referring to FIG. 7, after deployment and a subsequent delay, theactivation mechanism 106 activates the delay mechanism 104 by releasingthe first portion 130 of the restraining link 114 from the secondportion 132, which allows the compression spring 30 to urge thesecondary firing pin 28 to the secondary detonator 22. While not beinglimited to a particular theory, the activation mechanism 106 is offsetfrom the channel 32 that houses the delay mechanism 104. The activationmechanism 106 includes a container 56 (e.g., glass ampoule) holding areactant fluid 58. The reactant fluid 58 is a corrosive agent (e.g.,acid or solution of liquid or gas) that when placed in contact with therestraining link 114, chemically attacks and causes the restraining linkto erode, fail and break, thereby allowing the compression spring 30 toseparate and move the axial rod 110 and the secondary firing pin 28toward and activate the secondary detonator 22.

The activation mechanism 106 also includes an ampoule breaker 134, acompression spring 62 and a spring retainer pin 136. As shown in FIG. 7,the ampoule breaker 134 and compression spring 62 are aligned with atleast a portion of the container 56 in a channel 142 of the fuze slide16 offset from the channel 32. The compression spring 62 is anenergizing source mounted in a tension state inside the ampoule breaker134 between an inner wall 138 of the ampoule breaker and an inner wall140 of the slide 16. The spring retaining pin 136 is inserted into thefuze slide 16 and abuts a groove 142 of the ampoule breaker 134 to holdthe ampoule breaker in a locked position away from the container 56 asshown, for example, in FIG. 7. When inserted into the fuze slide 16 asshown, the spring retaining pin 136 keeps the compressed spring 62 inits tensioned state, and thereby keeps the container 56 safe from impactby the ampoule breaker 134. Therefore, the inserted spring retainer pin136 prevents activation of the SD fuze delay device 100.

Like the ampoule weight 60 described above, the ampoule breaker 134 is abreaking member that, but for the spring retainer pin 136, is urged bythe compression spring 62 into impact with the container 56, causing thecontainer to break and release the reactant fluid 58. In addition tobreaking the container 56, the ampoule breaker 134 also preferably actsas a plunger and pushes the released fluid 58 toward the delay mechanism104 whereupon the fluid corrodes the restraining link 114 to release thesecondary firing pin 28 toward the secondary detonator 22 (FIG. 11).

In a preferred embodiment, such as exemplified in FIG. 7, the fuze delaydevice 100 also includes a cushion pad 144 between the container 56 andthe closure plate 122. The cushion pad 144 is preferably a resilientmember that serves as a cushion to the container 56 before the containeris broken by the ampoule breaker 134. Submunitions 12 are subject to arange of vibrations, rattles and forces before deployment, for exampleduring loading and transportation, which transfer to the elements insidethe submunition. Since the container 56 is breakable, it is beneficialto include a cushion pad 144 adjacent the container to absorb thevibrations and prevent the container from moving and breakingprematurely. Accordingly, the cushion pad 144 is not required for theoperation of the invention, but is helpful to protect the container 56.

The self-destruct fuze delay device 100 self-destructs the submunition12 after a preset delay if the submunition fails to explode upon itsimpact with the ground or a target. FIG. 8 depicts an exemplary fuzeassembly 150 for the submunition 12 in a side view partially in section,before deployment into the atmosphere. FIG. 9 depicts the fuze assembly150 viewed from a side substantially orthogonal to the side view of FIG.8. The fuze assembly 150 includes the fuze delay device 100 mountable ona submunition 12, a ribbon retainer 152 and a stabilizer ribbon 154. Theribbon retainer 152 is attached to the safety lockout pin 46 and thespring retainer pin 136, both of which are shown inserted into the fuzeslide 16 to hold the secondary firing pin 28 and the ampoule breaker 134in their respective locked positions as shown, for example, in FIG. 7.The ribbon retainer 152 also prevents premature unfurling of thestabilizer ribbon 154 as is well known to those skilled in the art. Thefuze assembly 150 is shown in FIGS. 8 and 9 as having a safety spacer156 that is a known in-process safety device for blocking the firing pinfrom engaging the primary detonator 18 during the assembly of the fuzeassembly. The safety spacer 156 is removed from the fuze assembly 150before the submunitions 12 are stacked or otherwise loaded into theircarrier.

FIG. 10 is a flow diagram depicting an exemplary function sequence ofevents for the self-destruct fuze delay device 100 of the preferredembodiments. When an exemplary submunition 12 hits the air stream atdeployment (Step 200), the spring retainer 10, 136 and the safetylockout pin 146 are released out of their predeployment positions by theunfurling of the stabilizer ribbon 154. In other words, upon deployment,atmospheric wind resistance against the submunition 112 separate theribbon retainer 152 from the submunition, extracting the spring retainerpin 136 and the safety lockout pin 146 out to their predeploymentpositions by the unfurling of the stabilizer ribbon 154 at Step 202. Ascan be seen in the corresponding side views of FIGS. 11 and 12, theribbon retainer's separation from the submunition 12 extracts the springretainer pin 136 and the safety lockout pin 46 as the ribbon retainer152 separates. The safety and retainer pins 46, 136 may otherwise beextracted from the fuze delay device 100 by alternative approaches, andthe manner in which the pins are released from the fuze delay device isnot critical to the operation of the invention.

The extraction of the safety lockout pin 46 removes the lockout from thedelay mechanism 104, and the extraction of the spring retainer pin 136releases the compression spring 62. Upon its release at Step 204, thecompression spring 62 drives the ampoule breaker 134 into the container56, breaking the container and releasing the reactant fluid 58 to flowto the restraining link 114, preferably via the wick 54. To helpfacilitate the flow of the released fluid 58 to the wick 54 andrestraining link 114, a liquid passage 158 within the aperture 108 isprovided therebetween.

As can best be seen in FIG. 13, after the ampoule breaker 134 breaks thecontainer 56, the ampoule breaker continues to push beyond its impactpoint with the container 56. In this manner, the ampoule breaker 134acts as a plunger and pushes the fluid 58 through the liquid passage 158to the wick 54 and restraining link 114. In other words, after breakingthe container 56, the compression spring 62 continues to drive theampoule breaker 134, forcing the fluid 58 through the liquid passage 158and into the wick 54 at Step 206. The fluid 58 is absorbed by the wick54 and communicates with the restraining link 114. At this time, thedetonating fuze 102 appears as can best be seen, for example, in FIG. 13with the ampoule breaker 134 extended, the container 56 ruptured, andthe wick 54 saturated by the reactant fluid 58. FIG. 13 also shows thecushion pad 144 saturated with the reactant fluid 58, which is notimportant to the invention, but is instead a byproduct of the fluidexposed to the resilient cushion pad.

The wick 54 encircles an area (e.g., weakened area) of the restraininglink 114, and directs the reactant fluid 58 to access and attack (e.g.,erode, corrode) the restraining link at Step 208. Preferably the fluid58 erodes the restraining link in contact with the wick 54. In otherwords, the axial rod 110, the piston 112, the compression spring 30 andthe secondary firing pin 28 are preferably made of metal and notvulnerable to erosion by the reactant fluid 58.

At Step 210, over a predetermined time period (e.g., between about 25seconds and 30 minutes the restraining link 114 exposed to the reactantfluid 58 weakens to a point of failure and breaks, thus defining thefirst and second portions 130, 132. The predetermined time periodtypically varies in accordance with several factors, for example, thecomposition of the reactant fluid, the density of the restraining linkand the ambient temperature, as would be readily understood by a skilledartisan. For example, at cold temperatures of about −25° F., therestraining link fails at about 20 to 29 minutes. Of course the failuretime decreases as the temperature increases.

Upon the failure of the restraining link 114 at Step 212, thecompression spring 30 drives the first portion 130 of the restraininglink 114, the piston 112, the axial rod 110 and the secondary firing pin28 toward the secondary detonator 22, causing the secondary firing pinto impact and explode the secondary detonator 22. See, for example, FIG.14, which depicts the secondary firing pin 28 at impact with thesecondary detonator 22 after the failure of the restraining link 114.While the restraining link 114 shown in FIG. 14 is separated adjacentthe axial rod 110, it is understood that the failure of the restraininglink occurs at its weakened area preferably adjacent the wick 54. InFIG. 14, the weakened area of the restraining link 144 extends withinthe wick 54 between the axial rod and the closure plate 122.

As can best be seen in FIG. 14, at Step 214 output from the explodedsecondary detonator 22 initiates the adjacent primary detonator 18,causing it to explode and sterilize the submunition when the fuze slide16 is not armed. However, if at this time the fuze slide 16 is in itsarmed position, such that the primary detonator 18 is aligned with themain charge, then at Step 216 the initiation of the primary detonatorfrom the secondary detonator 22 will then fire the main charge anddestroy the submunition 12 (e.g., grenade, rocket warhead munition).Accordingly, the self-destruct fuze delay device 100 also ensuressterilization or destruction of the submunition 12 depending on therelationship between the primary detonator 18 and the main charge.

It is understood that the method and mechanism for making and using theself-destruct fuze delay device described herein are exemplaryindications of preferred embodiments of the invention, and are given byway of illustration only. It other words, the concept of the presentinvention may be readily applied to a variety of preferred embodiments,including those disclosed herein.

While the invention has been described in detail and with reference tospecific examples thereof, it will be apparent to one skilled in the artthat various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof. For example, the SD fuzedelay device is applicable to all the various ICM items including thesubmunitions of the GMLRS warheads and even non-rotating submunitions(e.g., MLRS, rocket warhead). For non-rotating submunitions, deploymentinto the air stream causes vibration sufficient to move the fuze slideinto its armed position. Accordingly and preferably, upon deployment ofrotating or non-rotating submunitions into the atmosphere, the ribbonunfurls, the safety and retainer pins extract, and the fuze slide movesto its armed position. Moreover, while the wicks are shown encirclingthe weakened area of the restraining link, it is understood that suchpreferred relationship is not required, as long as the wick is adjacentthe weakened area to expedite the desired failure. Without furtherelaboration, the foregoing will so fully illustrate the invention thatother may, by applying current or future knowledge, readily adapt thesame for use under various conditions of service.

1. A self-destruct fuze delay device for a submunition, the submunitionhaving a longitudinal axis, a main charge and a detonating fuze forinitiating the main charge upon impact, the detonating fuze having amovable slide, said self-destruct fuze delay device comprising: adetonator mounted to the movable slide; a delay mechanism arranged onthe movable slide offset and substantially orthogonal to thelongitudinal axis, said delay mechanism including an energizing source,a restraining link having a first portion and a second portion, and aself-destruct firing pin attached to said restraining link at said firstportion proximate to said detonator, said second portion longitudinallyextending from said first portion distal to said detonator and attachedto the movable slide, said first portion being moveable from a firstposition, in which it is held by its attachment to said second portionat a predetermined distance from said detonator, to a second position inwhich said first portion is separated from said second portion, and saidself-destruct firing pin is urged toward said detonator by theenergizing source; and an activation mechanism, in fluid communicationwith said delay mechanism, that releases said first portion from saidsecond portion after a predetermined delay, with said second portionremaining attached to the movable slide after separation from said firstportion.
 2. The device of claim 1, wherein said restraining link has amaterial composition different than said self-destruct firing pin, saidactivation mechanism causing said restraining link to fail and releasesaid first portion from said second portion.
 3. The device of claim 1,wherein said activation mechanism includes a container holding a fluidfor corroding said restraining link to release said first portion fromsaid second portion, and a breaking member that impacts said containerto release said fluid toward said restraining link.
 4. The device ofclaim 3, wherein said activation mechanism further includes a secondenergizing source that causes contact between said container and saidbreaking member.
 5. The device of claim 4, wherein said secondenergizing source is a compression spring.
 6. The device of claim 4,wherein said container is a glass ampoule and said breaking member is anampoule weight that is urged by said second energizing source to contactand break said glass ampoule to release said fluid.
 7. The device ofclaim 3, wherein said fluid comprises a reactant to said restraininglink.
 8. The device of claim 3, further comprising a wick adjacent saidrestraining link at a predetermined area between said first portion andsaid second portion, said wick arranged to collect said fluid from saidcontainer and isolate said fluid onto said predetermined area tofacilitate the corroding of said restraining link.
 9. The device ofclaim 3, said activation mechanism further including a retainer pin thatmaintains separation between said container and said breaking memberprior to a deployment of the submunition.
 10. The device of claim 3,further comprising a cushion pad between said container and the moveableslide.
 11. The device of claim 1, wherein said energizing source is acompression spring.
 12. The device of claim 1, the detonating fuzehaving a main detonator movable between a safety position and an armedposition, wherein the urging of said self-destruct firing pin toward thedetonator by said energizing source causes said self-destruct firing pinto contact and explode said detonator, which explodes said maindetonator.
 13. The device of claim 12, wherein the explosion of saidmain detonator initiates the main charge and destroys the submunition toexplode when said main detonator is in the armed position.
 14. Thedevice of claim 1, wherein said restraining link includes apredetermined weakened area between said first portion and said secondportion that breaks to release said first portion from said secondportion.
 15. A self-destruct fuze delay device for a submunition, thesubmunition having a longitudinal axis, a main charge and a detonatingfuze for initiating the main charge upon impact, the detonating fuzehaving a movable slide, said self-destruct fuze delay device comprising:a detonator mounted to the movable slide; a delay mechanism arrangedwithin the submunition substantially orthogonal to the longitudinalaxis, said delay mechanism including an energizing source, a restraininglink having a first end attached to said self-destruct firing pin and asecond end attached to the movable slide, said self-destruct firing pinbeing moveable from a first position, in which it is held by itsattachment to the movable slide at a predetermined distance from saiddetonator, to a second position in which said restraining link isseparated between said self-destruct firing pin and the movable slide,and said self-destruct firing pin is urged toward said detonator by saidenergizing source; and an activation mechanism that releases saidrestraining link from attachment to the movable slide, said activationmechanism including a container holding a fluid for corroding saidrestraining link, and a wick adjacent a predetermined area of saidrestraining link, said wick being porous to absorb and draw said fluidfrom said container onto said restraining link at said predeterminedarea to facilitate the corroding and separation of said restraininglink.
 16. The device of claim 15, said restraining link having a firstportion proximate to said detonator and attached to said self-destructfiring pin, and a second portion distal to the detonator and attached tothe movable slide, wherein said restraining link separates underchemical attack, with said second portion remaining attached to themovable slide after the separation.
 17. The device of claim 15, whereinsaid predetermined area of said restraining link is structurally weakerand more vulnerable to chemical attack than said self-destruct firingpin.
 18. The device of claim 15, wherein said container is a glassampoule, and further comprising a breaking member that contacts andbreaks said ampoule to release said fluid toward said restraining link.19. A method of self destructing a detonator of a submunition upondeployment into the air, the submunition having a detonating fuze with amovable slide, comprising: (a) releasing an activation liquid from acontainer; (b) absorbing the activation liquid with a porous wick; (c)directing the absorbed activation liquid onto a predetermined area of arestraining link attaching a firing pin to the movable slide; (d)corroding the predetermined area with the directed activation liquid;(e) separating the restraining link at the predetermined area; (f)urging the firing pin toward the detonator; (g) colliding the firing pininto the detonator to destroy the detonator.
 20. The method of claim 19,wherein Step (e) further comprises separating the restraining link atthe predetermined area into a first portion attached to the firing pinand a second portion remaining attached to the movable slide.